ECN Forum Forums General Topics of the Trade General Discussion Area Non-Contact Voltage Detector Concerns

Scott, are you absolutely certain that pocket testers such as the Fluke and Amprobe work a the electrostatic field and not the inductive coupling? By the way, since I went to work building a new 345KV switchyard's control room, and wiring up four big ABB GCB's (SF6 gas filled circuit breakers)any control wiring in the yard, including the 3 phase 240v. convenience outlets, only a meter will reliably confirm a circuit is dead. The "static" is so high that any length conductor is going to show "hot" even though it is not. It is tough to even get up on a 6' ladder and touch a grounded box, or get out of a work truck and not get bit by the "static". The reason I'm using parenthesis around the word "static" is that the linemen and high-voltage industry commonly referes to it as static, but in reality it is electromagnetic induction.

I'm not sure how they work either, but as long as they work...
I did tell my employees about the testers not working in relationship to moisture.
One of my men was working outside the other day and sweating. He also keeps his GB "ticker" clipped to the inside of his T-shirt. He said when he was working outside that day he couldn't get the tester to work reliably. Thanks for sharing the information guys, it may save someone some day.
I always tell my guys that the testers always tell you if the power is on but not necessarily if the power is off...use a meter.
Also, I know that if you are under high-tension / high-voltage wires that if you hold your tester in the air it will beep like there is constant voltage.

The effects on the tester with the water soaked NM points towards a Capacitive Coupling Effect, more than an Inductive Coupling effect, so that's where I formed the basis of Cap effect [like Cap Proxy].

Inductive Coupling would be an answer to Steve's tester having a stronger signal with higher loads, but could also fall back to Capacitive Coupling just as easilly.

Seems the tester would have to be self calibrating to sense Inductively on a circuit which could be idle or drawing 100 amps. At idle, there's very little Xl present [or Inductive Coupling between active circuit conductors and the enviroment surrounding them]. At high load, there's quite a lot of Inductive coupling between the active conductors, High Inductance surrounding the conductors, and higher coupling to surrounding enviroment [due to higher mag fields surrounding the conductors].
This should yield variable test responses at different distances - per load conditions - but not have a draining effect from water.

If you have other information regarding this, please pass it on!!!

I am going on theories only. Personally I do not use these types of testers, only have seen others use them [and seen contridictary reports from the tests! making me unsure of their use].

Scott SET

hi,
these type testers only work on AC circuits...not ANY circuit. they detect a the magnetic field created around the conductor when AC is applied.
-regards

frodo

[This message has been edited by frodo (edited 04-21-2002).]

I was under the impression that a magnetic field was present only when there was current flow.If there is no load on the ckt,thus no current flow,the detector will show the presence of voltage through the electro static field(capacitive coupling).
I THINK!

Chris

man it's early, didn't realize that the last post on here was from 2002! oops!

Hey, threads like this are timeless, that doesn't matter! What was your original comment?

Luketrician

I’m glad you bumped this tread up
I for one fall into the "use the volt pen from habit" group. Though I use it mostly in the classroom for fault finding when the students get circuits wrong.
I have never used it out in damp places. So I for one have never came across this situation but I will now rethink some of my faultfinding techniques

Kenny